The present invention relates to a device for automatically effecting exchange of measuring tools in a measuring machine or a measuring robot, which substantially comprises a movable measuring arm operable to support a measuring tool, provided with a feeler which is carried in contact with the surface of the workpiece to be measured.
As is known, measuring tools of machines of this type are constituted by sensors provided with a feeler member carried into contact with the surfaces of the workpiece to be measured, which feelers are able to generate electrical signals to be sent to an electronic calculator and suitably processed for providing the required dimensional data.
In known machines of this type the tools are fixed to a tool carrier device connected to the end of a movable measuring arm of the machine and their replacement on the tool carrier is effected manually. Moreover, each replacement operation of the tool inevitably involves the performance of supplementary operations on the machine for the purpose of rigorously positioning the three coordinate axes of each feeler with respect to the coordinate axes of the fixed frame of reference (operation of resetting of the tool). Since, for detecting the dimensions and form of a rather complex mechanical workpiece it is necessary to change the tools many times, each tool being particularly adapted to investigate a portion of the surface of the workpiece itself, the overall time required for effecting manual assembly and dismantling operations and for resetting the tools is rather high; moreover, measuring errors can occur if the tool resetting operations are not rigorously performed.
There are also known machines of this type in which the tool carrier is provided with a plurality of tools of different form and dimensions, each of which is particularly adapted to investigate a predetermined portion of the surface of the workpiece, in this case, to bring a new tool into the working position it is not necessary to effect a tool replacement operation, but the tool can be carried into the correct operating position by acting on means with which the tool carrier itself is provided.
Although in this case the times necessary to change each tool for the successive one are significantly reduced, there is however, the disadvantage that the assembly constituted by the tool carrier and the various tools connected to it is rather bulky and does not allow the operating freedom which would be obtained if only a single tool were mounted on the tool carrier; in fact, the tools which are not utilised in any one cycle of measurement can interfere with parts of the surface of the workpiece, thereby significantly limiting the freedom of displacement of the head of the machine. The object of the present invention is that of providing a device for automatically effecting exchange of measuring tools in a measuring robot or machine of the type first indicated, by means of which the above described disadvantages can be eliminated and therefore by means of which it will be possible to effect, without intervention by an operator, exchange of tools on the head of the machine with such a high precision that it is no longer necessary to effect resetting of the tool upon each tool change.